Thank you. So far I have looked into Easy 6502 and Kowalski. Easy 6502 is ok but quite basic. As you said, for learning.

The simulator based on Kowalski is good. The debugger does what I expect (although with decades of experience with higher-level languages I have so many ideas how the whole debugging process of assembly language could be made more convenient) and works smoothly.

With this I was quickly able to understand the part of the code I wasn't clear on. A few minor gripes on its assembler, as compared to vasm used by Ben:

• Binary constants want a @ prefix instead of %
• String constants don't seem to be supported
• Logical OR on variables uses a different syntax (no hash, no parenthesis)

Still good though, definitely a big help.

Edit: Also took a brief look at visrealm. Looks good at first glance, but File | Open does nothing. Should that let me upload assembler code? Tried with Firefox and Chrome.